Figure 3.

Kinetics of antigen-specific IgG secreting plasma cells and memory B cells post-TTC immunisation. At day 134 post-primary TNP-conjugated immunisation, all calves were subcutaneously immunised with 3 mg TTC in IFA then boosted 63 days later with the same immunising antigen. Blood samples were taken at various time-points following these immunisations. The time of primary and boost TTC immunisations are indicated by vertical dotted lines (day 134 and 197 pi, respectively). Antigen-specific IgG, plasma cell (A) and memory B cell (B) numbers were determined by B cell ELISPOT and are identified as follows: CGG-specific (open triangle), TTC-specific (crosses) and TNP-specific (closed triangle) IgG secreting ASCs. Results were expressed as ASC per 10⁶ PBMC for plasma cells and induced ASC per 10⁶ cultured PBMC for memory B cells (mean of determinations from individual calves in each group for the TNP- and CGG-specific responses, n = 5, and mean of determinations from all calves for the TTC-specific responses, n = 10). ^a = p < 0.05, ^b = p < 0.001.